Alkylation products of pyrazolanthrones



Patented June 24, 193d UNITED STATES PATENT OFFICE PAUL NAWIASKY ANDARTUR KRAUSE, 0F LUDWIGSHAFEN-ON-THE-RHINE, AND ALFRED HOLL, OFOFFENBACH-ON-THE-MAIN, GERMANY, ASSIGNORS TO GENERAL ANILINE WORKS,INC., OF NEW YORK, N. Y., A CORPORATION OF DELAWARE ALKYLATION PRODUCTSOF PYRAZOLANTHRONES No Drawing. Application filed December 21, 1926,Serial No. 156,256, and in Germany December 22, 1825 This inventionrelates to the production of alkylation products of pyrazolanthrones.

We have now found that the pyrazolanthrones obtainable according to theprocess of the German Patent 171,293 are transformed into alk'ylationproducts by the action of alkyl compounds containing at least oneinterchangeable substituent on pyrazolanthrone or its nuclearsubstitution products which term is meant to comprise compoundscontaining in their structure not more than one pyrazolanthrone residue.The compounds thus obtained are regarded as alkylpyrazolanthrones andalqylene-di-pyrazolanthrones.

For example, alkyl pyrazolanthrones are obtainable by the treatment ofpyrazolanthrone or its nuclear substitution products with alkylatingagents such as the alkyl halogenides, alkyl esters of sulfuric acid orof aromatic sulfonic acids and the like. This reaction may be carriedout in various Ways. -Thus, for example, the treatment may be carriedout in the usual manner in the presence of agents capable of combiningwith acids. Or it may be effected with the alkali metal salts ofpyrazolanthrones in aqueous solution, or by heating the said alkalimetal salts with alkyl halogenides in the absence of any solvent ordiluent and with or without the aid of catalysts. Generally the reactiondoes not proceed uni-iormly, and as a rule a mixture of varyingproportions of different products is obtained which it is more or lesseasy to separate. Thus, pyrazolanthrone when treated with the methylester of toluene sulfonic acid, in the presence of sodium carbonate intrichlorbenzene, furnishes a product from which two substances ofentirely different character can be separated. Only one of these twosubstances is capable of forming vat dyestuffs with alkaline condensingagents. In some cases only thecompound unsuitable for the production ofvat dyestuffs is formed.

We have found that these difliculties in the production of thealkyl-pyrazolanthrones suitable for being converted into vat dyestuffsmay be obviated and uniform products may be obtained if pyrazolanthronesare treated with alkylating agents in presence of acid condensingagents. Very suitably, the pyrazolanthrones may be alkylated by heatingto an elevated temperature wit-h the alkyl esters of sulfuric acid or ofaryl sulfonic acid, or suitable mixtures of a pure alcohol and sulfuricacid, which mixtures are to be regarded as equivalents of sulfuric'acidalkyl esters.

Alkylene-di-pyrazolanthrones are obtainable by the action on alkalimetal compounds of pyrazolanthrone or its nuclear substitution products,of alkyl compounds containing two interchangeable substituents such forexample as di-halogen compounds of paraffin hydrocarbons, for examplemethylene chlorid, ethylene bromid, or' 1.2-dibr0mpropane, or di-arylsulfonic acid esters of glycols such as ethylene glycol di-toluenesulfonic acid ester, and the like. In the case of the production ofdyestuffs from alkylenedi-pyrazolanthrones, no attention need be paid tothe properties of these compounds as it has not been observed up to nowthat several compounds of different properties are formed as in the caseof alkyl-pyrazolanthrones.

The following examples further illustrate how the invention may becarried out in practice, but the invention is not restricted thereto.The parts are by weight.

Example 1 E wample 22 parts of pyrazolanthrone are dissolved in 57.5parts of caustic soda lye of B. strength and 200 parts of Water, with anaddition of 80 parts of ethyl alcohol. 50 parts of dimethyl sulfate areslowly run into this solution at about 40 C., cooling being applied ifnecessary; in order to prevent the temperature from exceeding 40 C.After stirring for several hours, the methylation product is filteredoii, washed and dried. On crystallization from Inonochlorbenzene, it isobtained in the form of yellow crystals melti'ng'at about 161 (landdissolving in concentrated sulfuric acid to a yellowish red solutionshowing green fluorescence. The same product is obtained by suspendingthe pyrazolanthrone in water with an addition of caustic alkali solutionand adding the dimethyl sulfate at a moderately elevated temperature.The methylation product has the formula In a similar manner, ethylderivatives of pyrazolanthrone may be obtained.

Example 3 32 parts of methyl alcohol are slowly run into 120 parts ofconcentrated sulfuric acid at temperatures below 40 C. the additionheing accompanied by rapid stirring and cooling. 20 parts ofpyrazolanthrone are then introduced into the mixture, the whole beingfected by recrystallization from monochlorgradually raised to atemperature of 170 and there maintained for about 3 hours. Thecompletion of the reaction is indicated when a sample, taken from themelt and diluted with water, furnishes a precipitate which is no longersoluble in dilute caustic alkali solutions. The melt is then poured intowater and the product filtered off by suction, freed if necessary fromany unaltered original material by Warming with dilute alkali metalhydroxide, and dried. A complete purification of-the product may beofbcn-zeue. Monomethylpyrazolanthrone is obtained .in the form of yellowneedles melting at the temperature of to 224 C and has the formula l I Ti l i If fi-chlor-1.9-pyrazolanthrone be taken in place ofpyrazolanthrone, 5-chlormonom'ethyl-1.9-pyrazolanthrone, melting at thetemperature of 225 to 227 (3., is obtained which has the formula Theemployment of ethyl alcohol in place of methyl alcohol leads to anethylpyrazolanthrone.

E rample .4

E arample 5 20 parts of pyrazolan throne are stirred into a mixture of40 parts of sulfuric acid (66 Baum) and 40 parts of anhydrous boricacid, 60 parts of toluene' sulfonic acid methyl ester beingadded. Themixture is then heated, while stirring, to a temperature of 160 C. and.is maintained at that temperature for 2 hours. The further treatment isas in Example 4. Oncrystallization, the crude product furnishes theN-methyl-pyrazolanthrone described inExample 3.

Example 6 1 part of pyrazolan throne is heated for-scieral hours withthe same amounts of carbonate of soda and of themethyl ester of toluenesulfonic acid, in 30 parts of trichlorbenzene,

whereupon the latter is expelled by steam distillation. The residue canbe separated'into two isomericinonomethylpyrazolanthrones one of whichis identical with the product obtained according to Example 3, the otherof which forms yellow needles melting at the temperature of 184 to 187C. The separation may suitably be carried out by consecutive fractionalcrystallization from for instance methanol, glacial acetic acid or mono-I chlorbenzene.

E wample 7 The sodium compound of pyrazolanthrone is condensed withmethylene chlorid by heating with an excess of the latter at 140 to 150C. in an autoclave. not when crystallized from dichlorbenzene Thecondensation prod melts at 350 to 355 C. and has the composition asdetermined by analysis CH2 (C14H7ON2) 2- E'wample 8 A condensationproduct of ethylene bromide and the sodium compound of pyrazolanthronemay be obtained by heating the said sodium compound for example withtwice its weight of ethylene bromide to to C. When crystallized fromtrichlorbenzene,

it melts at 364 to 368 C. The product thus obtained has the formula Weclaim;

1. As new; articles of manufacture, compounds of p'araflimhydrocanbonswith at least one molecule of a pyrazolinthrone.

2. As new articles of manufacture, pyrazolantlirones containing at leastone alkyl group in the pyrazol nucleus.

As new article of manufacture, N-methyl-pyrazolanthrone which, whenpure, forms yellow needles melting at 221 to 224 C.

In testimony whereof we have hereunto set our hands.

PAUL NAWIASKY. ARTUR KRAUSE. ALFRED HOLL.

